Surgical technique and apparatus for proximal humeral fracture repair

ABSTRACT

A method and apparatus of reattaching a bone fragment to a proximal humerus of a humerus in a shoulder joint. The method includes introducing a distal end of the humeral nail into a medullary canal of the humerus. A first proximal screw is engaged with the bone fragment and a first proximal bore in the proximal end of the humeral nail to move the bone fragment toward the proximal humerus. The humeral nail and the attached bone fragment are rotated relative to the medullary canal of the humerus to position the bone fragment to an anatomically optimal location. The bone fragment is preferably one of a greater or lesser tuberosity of the proximal humerus. The method and apparatus can be used to reattach bone fragments in a variety of other joints.

This application claims priority to U.S. provisional patent application 61/051,320, filed May 7, 2008 herein incorporated by reference.

TECHNICAL FIELD

The present invention relates to a method and apparatus for fixation of proximal humeral fractures. In particular, the present invention relates to a humeral nail for reduction and orientation of the tuberosities at a humeral fracture site.

BACKGROUND OF THE INVENTION

As illustrated in FIG. 1, the humerus 100 of the upper arm is part of a “ball and socket” joint at the shoulder 102. The proximal humerus 102 includes a large rounded humeral head 106 joined to the humerus shaft 116 by a humeral neck 108 and two eminences, the greater and lesser tuberosities 110, 112.

Proximal humeral fractures are the most common humeral fractures. These are often found in patients who have fallen on their arms, creating an axial load on the humerus 100 that causes a fracture of the humeral head 106. In a two-part fracture, the humeral head 106 or a single portion of the head is broken from the humeral shaft 116. In more severe fractures, the humeral head 106 tends to fracture from one or both of the tuberosities 110, 112. As illustrated in FIG. 1, upon occurrence of a fracture the muscles 104 attached to the tuberosities 110, 112 and the humeral shaft 116 pull the humeral head 106, tuberosities 110, 112, and humeral shaft 116 in the directions indicated and away from the correct anatomical positions.

To repair a complex fracture such as illustrated in FIG. 1, a separate reduction device is used to position and retain one or more of the humeral head 106, tuberosities 110, 112, and humeral shaft 116 in the correct anatomical position. As used herein, “reduce” or “reduction” refers to positioning a bone fragment to an anatomically optimal position.

The humeral head 106, tuberosities 110, 112, and humeral shaft 116 are then secured using conventional techniques such as external fixation, percutaneous pinning, plating, intramedullary nailing, shoulder arthroplasty, and others. These methods, however, are not entirely suitable for treatment of more complex fractures, or when tissues are weakened by disease. In these cases, surgical replacement of the shoulder joint is often required.

U.S. Pat. No. 5,472,444 (Huebner et al.) discloses use of a humeral nail for fixation of proximal humeral fractures. Huebner provides an elongated tapered nail or rod having an elongated body with a curved tapered shank that may be secured within a proximal portion of the humeral shaft, with a contiguous proximal portion of the nail extending proximally from the shank to provide a solid foundation to which the humeral head fragments may be secured. The proximal portion has transverse holes oriented at selected angles to receive fasteners attached to the fragments. Huebner does not, however, provide a mechanism to reduce the fracture and retain the fragments during fixation. Also, if a screw is not accurately located in the fragment, Huebner does not provide a mechanism to adjust the location of the fragment relative to the humeral head.

SUMMARY OF THE INVENTION

The present invention relates to a system and method for repairing a proximal humeral fracture using a humeral nail for both reduction and retention of the fragments to the correct anatomical position. The system and method provides for limited rotation of the humeral nail within the medullary canal to adjust the position of a bone fragment relative to the humeral head.

In the preferred embodiment, the procedure is performed entirely percutaneously without the use of a reduction device. Small incisions are made in the skin at selected locations, rather than requiring the entire shoulder joint to be exposed. The humeral nail can be inserted percutaneously, with minimal risk of damage to the rotator cuff. The positioning of the proximal screws limits interference with the articular surface of the humeral head. In the preferred embodiment, no screws are required to retain the humeral head in its anatomical position. Rather, the humeral head is retained medially by the glenoid, anteriorly and posteriorly by the rotator cuff muscles and the tuberosities and superiorly by rotator cuff muscle.

An aiming device is required to position the screws to engage with the corresponding bores in the humeral nail. In one embodiment, the aiming device is attached to the humeral nail. The aiming device is preferably constructed from a radiolucent material to permit imaging when reconstructing the fracture and locating the nail and the screws. In another embodiment, the aiming device involves various imaging techniques. As used herein, “imaging” refers x-ray, MRI, CAT-scan, ultrasound, fluoroscopy, and the like. As used herein, “aiming device” refers to both mechanical devices and imaging devices.

The humeral nail is positioned in the medullary canal in the humerus. The humeral nail is preferably substantially straight which permits it to rotate after insertion in the medullary canal and helps avoid the need to insert the nail through the insertion of the cuff. A first proximal screw is used to move one of the greater or lesser tuberosities fragmented from the humerus toward the humeral nail. The distal tip of the first proximal screw is preferably not advanced substantially beyond the humeral nail. Consequently, the fragment of the greater or lesser tuberosity attached to the humeral nail and the humeral nail itself can be rotated without damaging surrounding bony structures and soft tissues. After the initial movement of the fragment of the greater or lesser tuberosity by the first proximal screw, the attached fragment of the greater or lesser tuberosity is reduced by rotation with the humeral nail to an anatomically optimum position.

The present invention is also directed to a method of reattaching a bone fragment separated from a proximal humerus in a shoulder joint. The method includes introducing a distal end of the humeral nail into a medullary canal of the humerus. A first proximal screw is engaged with the bone fragment and a first proximal bore in the proximal end of the humeral nail to attach the bone fragment to the humeral nail. The humeral nail and the attached bone fragment are rotated relative to the medullary canal of the humerus to position the bone fragment to an anatomically optimal location. The bone fragment is preferably one of the tuberosities.

The humeral nail is optionally rotationally oriented relative to the bone fragment before engaging the first proximal screw. An aiming device is optionally used to locate the first proximal screw relative to the humeral nail. In one embodiment, the aiming device is attached to a proximal end of the humeral nail.

The first proximal screw is preferably advanced in the first proximal bore so that a distal end of the first proximal screw does not substantially extend past the humeral nail. A second proximal screw is engaged with the proximal humerus and a second proximal bore in the proximal end of the humeral nail to prevent further rotation of the humeral nail. The entire procedure is preferably performed percutaneously. The humeral head is preferably retained laterally and inferiorly by the tuberosities, medially by a glenoid of the shoulder joint, and superiorly, anteriorly and posteriorly by a rotator cuff tendon of the shoulder joint, without the use of screws. That is, the humeral head is retained to the proximal humerus solely with anatomical features of the shoulder joint.

The present invention is also directed to a method of reattaching a bone fragment to the proximal humerus. The method includes attaching an aiming device to a proximal end of a substantially straight humeral nail. A distal end of the humeral nail is introduced into a medullary canal of the humerus. An aiming device is used to locate a first proximal screw through the bone fragment, into the proximal humerus, and into a first proximal bore in the proximal end of the humeral nail. The first proximal screw is advanced into the first proximal bore to stabilize the bone fragment relative to the humeral nail and, in some embodiments, to bring the bone fragment into engagement with the proximal humerus. The distal end of the first proximal screw preferably does not substantially extend past the humeral nail. The humeral nail is then rotated within the medullary canal of the humerus so that the bone fragment is reduced to an anatomically optimal location. A second proximal screw is engaged with the proximal humerus and a second proximal bore in the proximal end of the humeral nail to prevent further rotation of the humeral nail.

In one embodiment, the first proximal screw is shorter than a conventional fixation screw so as to not extend substantially beyond the humeral nail and interfere with rotation of the attached fragment and the humeral nail. That is, the screw is of adequate length to traverse the distance from the cortical wall to the humeral nail. In another embodiment, the first proximal screw is only partially advanced into the first proximal bore in the humeral nail. Only after reduction of the fragment through rotation of the humeral nail to an anatomically optimal location is the first proximal screw advanced the remainder of its length.

An aiming device is then used to locate additional screws to reduce and retain other fragments of the humeral head to the humeral nail. The aiming device is also preferably used to locate screws to distally-located bores in the humeral nail. In one embodiment, at least one distal screw is delivered with the forearm in a neutral rotation. The aiming device can be any of a variety of structures that are fixed or rotatable relative to the humeral nail.

One embodiment of the present invention is a humeral nail including a substantially linear elongate shaft having a proximal end and a distal end, a distal bore at the distal end of the elongate shaft and a plurality of proximal bores at the proximal end of the elongate shaft.

In some embodiments, a neutral axis is an intersection of a horizontal plane with a frontal plane containing a central axis of the humeral nail. As such, when the arm is in a neutral rotation position, the neutral axis is substantially perpendicular to the forearm. In some embodiments, an angulated location of the proximal screw(s) is measured with respect to the neutral axis.

One proximal bore is optionally positioned at between about 30 degrees and about 40 degrees relative to the neutral axis, also described as the neutral position. Another proximal bore is positioned at between about 90 degrees and about 100 degrees relative to the neutral position. Still another third proximal bore is positioned at between about 50 degrees and about 60 degrees relative to the neutral position.

Terminology such as “first,” “second,” “third,” etc., is used herein to designate particular components being described. Because various components of the embodiments described herein can be positioned in a number of different orientations and in a number of different sequences, this terminology is used for the purposes of illustration and is not intended to be read in a restrictive manner.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a perspective view of an exemplary proximal humeral fracture.

FIG. 2A is a perspective view of a humeral nail in accordance with an embodiment of the present invention.

FIG. 2B is a view similar of FIG. 2A, which shows the humeral nail in accordance with another embodiment of the present invention.

FIG. 3 is a top schematic view of the humeral nail implanted in the humerus in accordance with an embodiment of the present invention.

FIG. 4A is a schematic view of a proximal end of the humeral nail in accordance with an embodiment of the present invention.

FIG. 4B is a top cross-sectional view through lines A-A of FIG. 4A of the location of a second proximal bore of the humeral nail in accordance with an embodiment of the present invention.

FIG. 4C is a top cross-sectional view through lines B-B of FIG. 4A of the location of a third proximal bore of the humeral nail in accordance with an embodiment of the present invention.

FIG. 4D is a top cross-sectional view through lines C-C of FIG. 4A of the location of a first proximal bore of the humeral nail in accordance with an embodiment of the present invention.

FIG. 4E is a top cross-sectional view through lines D-D of FIG. 4A of the location of a fourth proximal bore of the humeral nail in accordance with an embodiment of the present invention.

FIG. 5 is a top view showing the respective angular offsets of a plurality of proximal screws in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 2A, 2B, 3, 4A-4E and 5 show a humeral nail 10. As shown in FIG. 3, this humeral nail is intended to be implanted in the humerus 100, shown in FIG. 1 already described, of a patient to fixate a fracture F at or proximate the greater tuberosity 110 and lesser tuberosity 112 of the proximal humerus. The humeral nail 10 includes a substantially linear shaft 12 having a proximal portion 14 and a distal portion 16. The humeral nail 10 is introduced through the humeral head 106 of the humerus 100 and extends within the humeral shaft 116 such that the distal end 16 of the humeral nail 10 is positioned within the medullary canal of the humeral shaft 116.

It will be noted that the shown humeral nail 10 is designed to be implanted in the right humerus of a patient. A humeral nail that is to be implanted in the left humerus of a patient will be a mirror-image of the humeral nail depicted in the figures.

In the preferred embodiment, small incisions are made in the skin at selected locations, rather than requiring the entire shoulder joint to be exposed. Percutaneous procedures preferably require incisions of less than about 3.81 centimeters, more preferably less than about 2.54 centimeters, and most preferably less than about 1.27 centimeters, although a variety of dimensions are contemplated. The humeral nail 10 can be inserted percutaneously, with minimal risk of damage to the rotator cuff.

Although the humeral nail 10 is primarily discussed as being implanted in a patient's arm to fixate a proximal humeral fracture, the present method and apparatus applies equally well to fractures in other locations of a patient's body without departing from the intended scope of the present invention. For example, the humeral nail 10 may be modified to repair proximal or distal femoral fractures, proximal or distal radial fractures, etc.

In the preferred embodiment, the humeral nail 10 functions similarly to a device for repairing massive rotator cuff tears and is based on reattaching the greater and lesser tuberosities 110, 112 to fixate the fracture F, rather than stabilizing the humeral head 106. The humeral nail 10 is based on the horizontal plane and is thus able to fixate the fracture F without introducing a screw through the articular surface 106A of the humeral head 106. This is accomplished in part by reducing both the tuberosities 110, 112 and providing a stable platform for the humeral head 106. Using this methodology, the humeral nail 10 is designed to treat multi-part fractures (e.g., 2-part, 3-part, 4-part, etc.) in the horizontal plane using a simple and reproducible surgical technique. In addition, the humeral nail 10 can be percutaneously introduced at a location where the humeral head 106 intersects the tuberosities 110, 112, minimizing the invasiveness of the surgery. The fracture F is fixated using particular height and angulation specifications of the humeral nail 10.

FIGS. 2A and 2B show a perspective view of the humeral nail 10 in accordance with two embodiments of the present invention. FIG. 3 shows a top schematic view of the humeral nail 10 implanted in the humerus 100. FIGS. 2A, 2B and 3 will be discussed in conjunction with one another.

The shaft 12 of the humeral nail 10 is substantially linear and has a central axis CA extending through a length of the humeral nail 10. The substantially linear shape of the shaft 12 allows the humeral nail 10 to be rotated within the medullary canal without damaging surrounding bone and soft tissue. The proximal portion 14 of the humeral nail 10 includes a first proximal bore 18A, a second proximal bore 18B, a third proximal bore 18C and optionally, a fourth proximal bore 18D. The proximal bores 18A-18D are spaced from a proximal end 23 of the humeral nail 10 and each other at particular heights and angles to permit fixation of the fracture F at the humeral head 106. The third proximal bore 18C is positioned below the second proximal bore 18B, the first proximal bore 18A is positioned below the third proximal bore 18C and the fourth proximal bore 18D is positioned below the first proximal bore 18A, although a variety of respective heights and spacings are contemplated.

In one embodiment, the humeral nail 10 is formed of a bioresorbable material such as polylactide so that the humeral nail 10 does not have to be removed after the fracture F has healed. The humeral nail 10 may optionally be coated with a bone in-growth friendly coating, such as hyaluronate to facilitate cell proliferation and migration, or with an anti-septic coating, such as cement with an antibiotic.

The humeral nail 10 also includes a first proximal screw 26A that is engageable with the first proximal bore 18A, a second proximal screw 26B that is engageable with the second proximal bore 18B, a third proximal screw 26C that is engageable with the third proximal bore 18C and a fourth proximal screw 26D that is engageable with the fourth proximal bore 18D. Each of the screws 26A-26D includes a head portion and a body portion. In the illustrated embodiment, the head portion has a diameter that is about two times greater than a diameter of the body portion and has a substantially flat surface that is connected to the body portion. This design distributes pressure on the humerus 100 more uniformly. The body portion of each of the proximal screws 26A-26D is optionally threaded to aid in maintaining each of the screws 26A-26D within the proximal bores 18A-18D, respectively.

As can particularly be seen in FIG. 3, the lengths of the body portions of the screws 26A-26D may vary in length depending on the anatomy of the patient. The body portion of the first proximal screw 26A enters at the greater or lesser tuberosity 110, 112 depending on the location of the fracture F, and preferably has a length such that when fully inserted into the humeral nail 10, the body portion of the distal end 28 of the first proximal screw 26A does not substantially extend beyond the humeral nail 10. Thus, the first proximal screw 26A will affix a fragment of the greater or lesser tuberosity 110, 112 to the humeral nail 10, but will not extend to the other side of the humeral nail 10.

If the distal end 28 of the first proximal screw 26A extends beyond through the humeral nail 10, the body portion may catch soft tissue and bone if the humeral nail 10 is rotated within the humerus 100. Generally, the length of the body portion of the first proximal screw 26A is sufficient to extend from the cortical wall of the greater or lesser tuberosity 110, 112 to the central axis CA of the humeral nail 10. In one embodiment, the first proximal screw 26A is between about 25 millimeters (mm) and about 40 mm long. Because the humeral nail 10 is substantially linear and the body portion of the first proximal screw 26A does not extend substantially past the humeral nail 10, the humeral nail 10 with the attached bone fragment of the greater or lesser tuberosity 110, 112 can be rotated within the medullary canal M before additional screws, e.g., proximal screws 26B-26D and distal screws 38, 40 are inserted into the humeral nail 10.

Each of the body portions of the second, third and fourth proximal screws 26B-26D has a length sufficient to pass through its respective bore 18B-18D to the opposite side of the humeral nail 10. The lengths of the body portions of the second, third and fourth proximal screws 26A-26D may have varying lengths, but are generally longer than the first proximal screw 26A.

The first and second proximal screws 26A, 26B are positioned through the fragment of the greater or lesser tuberosity 110, 112 and function to reduce the fragment of the greater or lesser tuberosity 110, 112 and hold the fracture F together. Together, the proximal end 23 of the humeral nail 10 and the first, second and third proximal screws 26A-26C maintain the tuberosities 110, 112 and stabilize the fracture F.

In one embodiment, the proximal end 23 of the humeral nail 10 and the second and third proximal screws 26B, 26C are positioned in a triangular formation such that the fracture F is stabilized by three points: the proximal end 23 of the humeral nail 10, the second proximal screw 26B positioned through a posterior part of the greater or lesser tuberosity 110, 112 and the third proximal screw 26C positioned through an anterior part of the greater or lesser tuberosity 110, 112. In this configuration, the fracture F is maintained laterally and inferiorly by the tuberosities 110, 112; medially by the glenoid; and superiorly, anteriorly and posteriorly by the rotator cuff tendon, without requiring the fourth proximal screw 26D. In addition, the angulation between the first proximal screw 26A through the greater tuberosity 110 and the lesser tuberosity 112 is wide enough to reduce the greater or lesser tuberosity 110, 112 and rotate the humeral nail 10 without damaging the surrounding bone structures or soft tissues. The angulation is also wide enough to avoid cuff insertion when inserting the humeral nail 10 in the humerus 100 and still catch the greater tuberosity 110 and lesser tuberosity 112 at their centers.

The fourth proximal screw 26D functions to support the humeral head 106 and locks the humeral head 106 in position. While the humeral nail 10 is discussed as including a fourth proximal bore 18D and a fourth proximal screw 26D, the fourth proximal bore and screw 18D, 26D are not necessary for the humeral nail 10 to properly function and are thus optional. In the preferred embodiment, no screws are used to secure the humeral head 106. In particular, the humeral head 106 is retained laterally and inferiorly by the tuberosities 110, 112, medially by the glenoid and superiorly, anteriorly and posteriorly by the rotator cuff tendon (see FIG. 1).

Referring back to FIGS. 2A and 2B, the distal portion 16 of the humeral nail 10 includes a first distal bore 34 or 34′ and a second distal bore 36. In the embodiment of FIG. 2A, the distal bores 34 and 36 are spaced from one another but lie along the same axial line. In the preferred embodiment of FIG. 2B, the distal bores 34′ and 36 are not lying along the same axial line. In some embodiments, a neutral axis A is an intersection of a horizontal plane with a frontal plane containing a central axis CA of the humeral nail 10. As such, when the patient's arm is in a neutral rotation position, the neutral axis A is substantially perpendicular to the forearm. In the embodiments of FIGS. 2A and 2B, the neutral axis A is substantially parallel with an axis passing through each of the distal bores 34 and 36 and is substantially perpendicular to the central axis CA, whereas the axis of the distal bore 34′ is at a non zero angle relative to the neutral axis in either the postero-anterior direction or the antero-posterior direction. In a preferred embodiment, one of the distal bore axes is preferably parallel to the neutral axis. In the vertical plane, the distal bore axis is angulated relative to the central axis CA. In another preferred embodiment, in the vertical plane, the distal bore axis is preferably perpendicular to the central axis CA. As described, the angular locations of the screws 26A-26D are indicated relative to the neutral axis A.

A first distal screw 38 or 38′ is engageable with the first distal bore 34 or 34′ along the axis of the distal bore. A second distal screw 40 is engageable with the second distal bore 36 along the axis of the distal bore. The distal screws 38 or 38′ and 40 are preferably designed such that one is static and the other is dynamic. The first and second distal screws 38 or 38′ and 40 are in dotted lines in FIGS. 3A and 3B so that the first and second distal bores 34 or 34′ and 36 can be seen.

FIG. 4A shows a schematic view of the proximal portion 14 of the humeral nail 10 and will be discussed in conjunction with FIGS. 4B, 4C, 4D, 4E, and 5. FIG. 4B shows a top cross-sectional view through lines A-A of FIG. 4A of the location of the second proximal bore 18B, FIG. 4C shows a top cross-sectional view through lines B-B of FIG. 4A of the location of the third proximal bore 18C, FIG. 4D shows a top cross-sectional view through lines C-C of FIG. 4A of the location of the first proximal bore 18A and FIG. 4E shows a top cross-sectional view through lines D-D of FIG. 4A of the location of the fourth proximal bore 18D. As previously mentioned, the proximal bores 18A-18D are positioned at particular heights and angles relative to the neutral axis A. The particular heights and angles allow the humeral nail 10 to bring the greater or lesser tuberosity 110, 112 of the humerus 100 back to its anatomical position without damaging the humeral shaft 116 and surrounding soft tissue. The proximal bores 18A-18D are positioned in a postero-anterior or antero-posterior direction, also described as either internally or externally, relative to the neutral axis A of the humeral nail 10. When the proximal bore 18A-18D is positioned internally relative to the neutral axis A, the proximal bore 18A-18D is located in a first direction from the neutral axis A. When the proximal bore 18A-18D is positioned externally relative to the neutral axis A, the proximal bore 18A-18D is located in a second direction from the neutral axis A.

In the embodiment shown in FIG. 5, the second proximal bore 18B is located between about 7 millimeters (mm) and about 11 mm from the proximal end 23 of the humeral nail 10 and at an angle relative to the neutral axis A about 30 degrees and 40 degrees, particularly about 9 mm from the proximal end 23 of the humeral nail 10 and at an internal rotation of about 35 degrees. In one embodiment, the third proximal bore 18C is located between about 13 mm and about 17 mm from the proximal end 23 of the humeral nail 10 and at an external rotation of between about 90 degrees and 100 degrees, particularly about 15 mm from the proximal end 23 of the humeral nail 10 and at an external rotation of about 95 degrees. In one embodiment, the first proximal bore 18A is located between about 19 mm and about 23 mm from the proximal end 23 of the humeral nail 10 and at an internal rotation of between about 50 degrees and 60 degrees, particularly about 21 mm from the proximal end 23 of the humeral nail 10 and at an internal rotation of about 55 degrees. In one embodiment, the fourth proximal bore 18D is located between about 24 mm and about 28 mm from the proximal end 23 of the humeral nail 10 and at an external rotation of between about 25 degrees and 35 degrees, particularly about 26 mm from the proximal end 23 of the humeral nail 10 and at an external rotation of about 30 degrees. Besides, the axis of the distal bore 34′ is at an external rotation of between 15 degrees to 25 degrees relative to the neutral axis A.

In some embodiments, the angles as described above causes the screw axes to not only be in the tuberosities, but also at the insertion of the rotator cuff on the tuberosities. This can be particularly useful in patients with weak bones, where a screw would only be inserted into bone which it would otherwise pass through without being retained. Instead, and in accordance with some embodiments described herein, the angular offsets and relative positions of the screws facilitate insertion at the insertion muscle location, where the screws are retained by more solid bone and the muscle itself.

The method for reducing and orienting the tuberosities 110, 112 at a humeral fracture site will now be described in detail.

The humeral nail 10 is introduced through the humeral head 106 and into the medullary canal of the humerus 100. The humeral nail 10 is preferably inserted in a region of the humeral head 106 offset from the articular surface 106A. In one embodiment, the humeral nail 10 is introduced into the humerus 100 percutaneously or using a small superior trans-deltoid approach. The humeral nail 10 is preferably substantially straight which permits it to rotate after insertion in the medullary canal.

After the humeral nail 10 is positioned within the humerus 100, an aiming device is used to locate the first proximal screw 26A in one of the greater or lesser tuberosities 110, 112 and into the first proximal bore 18A. In one embodiment, an aiming device is attached to the humeral nail 10. The aiming device is preferably fixed relative to the central axis CA of the humeral nail, although a rotating aiming device may be used. In one embodiment, the aiming device is formed of a radiolucent material and allows the surgeon to see the fracture reconstruction, the location of the humeral nail 10 and the location of the proximal and distal screws 26A-26D, 38, 40. In another embodiment, the aiming device is attached to the humeral nail after the humeral nail is introduced into the medullary canal. Alternatively, the aiming device is an imaging device.

The first proximal screw 26A is used to move one of the tuberosities 110, 112 that has been fragmented toward the proximal humerus 102. The distal tip 28 (see FIGS. 3 and 5) of the first proximal screw 26A is preferably not advanced substantially beyond the humeral nail 10. The first proximal screws 26A is not intended to go into the humeral head 106, but rather to the border of the humeral head 106.

Next, the attached fragment of the greater or lesser tuberosity 110, 112 is reduced to an anatomically optimal position by rotation with the humeral nail 10. The fragment of the greater or lesser tuberosity 110, 112 attached to the humeral nail 10 can be rotated clockwise or counterclockwise around the central axis CA without damaging surrounding bony structures and soft tissues. Depending on the condition of the surrounding bony structure, the fragment of the greater or lesser tuberosity 110, 112 and the humeral nail 10 can be rotated between about zero and about 20 degrees, and preferably between about zero and about 40 degrees. In one embodiment, the fragment of the greater or lesser tuberosity 110, 112 is simultaneously moved towards the proximal humerus 102 and rotated toward an anatomically optimal position.

In another embodiment, the first proximal screw 26A is only partially advanced into the first proximal bore 18 in the humeral nail 10. Only after reduction of the fragment of the greater or lesser tuberosity 110, 112 to an anatomically optimal location by rotation of the humeral nail 10 is the first proximal screw 26A advanced the remainder of its length. Once the first proximal screw 26A is advanced into the humeral head 106, further rotation of the humeral nail 10 is not advised. Even in the fully engaged position, the distal end 28 of the first proximal screw 26A preferably does not penetrate the cortical bone on the articular surface 106A.

The aiming device is used to insert the remainder of the proximal screws 26B-26D into the humeral bores 18B, 18C, 18C. Once the proximal screws 26A-26D are secured through the proximal bores 18A-18D, respectively, the first and second distal screws 38, 40 are secured through the first and second distal bores 34, 36, respectively, in the distal portion 14 of the humeral nail 10 using the aiming device.

Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, while the embodiments descriconcave articular surface above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the descriconcave articular surface features. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof. 

1. A method of reattaching a bone fragment separated from a proximal humerus of a humerus in a shoulder joint, the method comprising the steps of: introducing a distal end of the humeral nail into a medullary canal of the humerus; engaging a first proximal screw with the bone fragment and a first proximal bore in the proximal end of the humeral nail to fix the attach the bone fragment to the nail; and rotating the humeral nail and the attached bone fragment relative to the medullary canal of the humerus to position the bone fragment to an anatomically optimal location.
 2. The method of claim 1, further comprising the step of rotationally orienting the humeral nail relative to the bone fragment before engaging the first proximal screw.
 3. The method of claim 1, further comprising the step of using an aiming device to locate the first proximal screw relative to the humeral nail.
 4. The method of claim 1, further comprising the step of attaching an aiming device to a proximal end of the humeral nail.
 5. The method of claim 1, further comprising the step of advancing the first proximal screw in the first proximal bore so that a distal end of the first proximal screw does not substantially extend past the humeral nail.
 6. The method of claim 1, further comprising the step of engaging a second proximal screw with the proximal humerus and a second proximal bore in the proximal end of the humeral nail.
 7. The method of claim 1, wherein the humeral nail and first proximal screw are implanted percutaneously.
 8. The method of claim 1, further comprising the step of engaging a plurality of proximal screws with the proximal humerus and a plurality of proximal bores in the proximal end of the humeral nail.
 9. The method of claim 1, further comprising the step of engaging at least one distal screw with the humerus and a distal bore in the distal end of the humeral nail.
 10. The method of claim 1, wherein engaging the first proximal screw comprises engaging the first proximal screw with a greater tuberosity of the proximal humerus, into the proximal humerus, and into the first proximal bore in the proximal end of the humeral nail.
 11. The method of claim 1, wherein engaging the first proximal screw comprises engaging the first proximal screw with a lesser tuberosity of the proximal humerus, into the proximal humerus, and into the first proximal bore in the proximal end of the humeral nail.
 12. The method of claim 1, further comprising the step of engaging another proximal screw with a proximal humeral and a proximal bore in the proximal end of the humeral nail, the other proximal screw being located about 30 degrees to about 40 degrees relative to a neutral axis.
 13. The method of claim 1, further comprising the step of engaging another proximal screw with a proximal humeral and a proximal bore in the proximal end of the humeral nail, the other proximal screw being located about 90 degrees to about 100 degrees relative to a neutral axis.
 14. The method of claim 1, wherein the first proximal screw is located about 50 degrees to about 60 degrees relative to a neutral axis.
 15. The method of claim 1, wherein rotating the humeral nail and the attached bone fragment within the medullary canal of the humerus comprises rotating the humeral nail and the attached bone fragment about zero degrees to about 40 degrees before a second proximal screw is engaged with the humeral nail.
 16. The method of claim 1, wherein a humeral head of the proximal humerus is retained medially by the glenoid, anteriorly and posteriorly by the rotator cuff muscles and the tuberosities, and superiorly by the humeral nail.
 17. The method of claim 1, wherein a humeral head of the proximal humerus is retained to the proximal humerus solely with anatomical features of the shoulder joint.
 18. The method of claim 1, wherein the humeral nail comprises a substantially linear shaft.
 19. The method of claim 1, wherein the angular offset and relative position of the proximal screw facilitates insertion of the screw at the insertion muscle location, where the screws are retained by substantially solid bone and the muscle.
 20. A humeral nail comprising: a substantially linear elongate shaft having a proximal portion, a distal portion, and a central axis and configured to define a neutral axis with respect to the central axis; at least one distal bore at the distal portion of the elongate shaft having a distal bore axis; a first proximal bore at the proximal portion of the elongate shaft positioned between about 50 degrees and about 60 degrees relative to a neutral axis in a postero-anterior direction; a second proximal bore at the proximal portion of the elongate shaft positioned between about 30 degrees and about 40 degrees relative to the neutral axis in a postero-anterior direction; a third proximal bore at the proximal portion of the elongate shaft positioned between about 90 degrees and about 100 degrees relative to the neutral axis in an antero-posterior direction; a first distal screw for engagement with the first distal bore; a first proximal screw for engagement with the first proximal bore; a second proximal screw for engagement with the second proximal bore; and a third proximal screw for engagement with the third proximal bore, wherein the first proximal screw has a length shorter than a length of the second and third proximal screws.
 21. The humeral nail of claim 20, wherein both the second and third proximal bores are positioned on one side of the first proximal bore along the elongate shaft.
 22. The humeral nail of claim 20, further comprising a fourth proximal bore at the proximal portion of the elongate shaft positioned between about 20 and about 40 degrees relative to the neutral axis in an antero-posterior direction.
 23. The humeral nail of claim 22, wherein both the second and third proximal bores are positioned on one side of the first proximal bore along the elongate shaft, whereas the fourth proximal bore is positioned on the opposite side of the first proximal bore.
 24. The humeral nail of claim 22, further comprising a fourth proximal screw for engagement with the fourth proximal bore, wherein the length of the first proximal screw is shorter than a length of the fourth proximal screw.
 25. The humeral nail of claim 20, wherein the distal bore axis of the at least one distal bore is substantially parallel to the neutral axis.
 26. The humeral nail of claim 20, wherein the distal bore axis of the at least one distal bore is at an angle of between about 15 degrees and about 25 degrees relative to the neutral axis in an antero-posterior direction.
 27. The humeral nail of claim 20, wherein at least two distal bores are provided at the distal portion of the elongate shaft.
 28. The humeral nail of claim 20, wherein at least one of the first, second, third and fourth proximal screws includes a head portion and a body portion, wherein the head portion has a diameter that is about two times greater than a diameter of the body portion, and further wherein the head portion has a substantially flat surface that is connected to the body portion. 